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Gammarus: Nature’s Waste Disposal Unit

Just as compost worms thrive in a media bed aquaponics system, the tiny Gammarus crustacean is ideal for Floating Raft and any Filtration systems where fish waste collects.

The Mighty Gammerus Photo courtesy of Michal Maňas

Behold the Mighty Gammarus!

by Damon Polta

Behold one and all, I’m here to tell you about one of natures unsung heroes,
All dramatics aside there is an organism that does a lot of work with very little credit.

Gammarus, commonly known as scuds in Northern America, are a tiny crustacean that lives basically everywhere on the planet in one form or another. There are over 200 species of Gammarus making them one of the animals on the planet that are most prolific – with the most variety, and you all thought there were many types of dogs and cats. There are fresh water types, salt water types, and brackish types of water.

These little guys are detritivores, which is a big word for waste eating organism. They eat anything dead and rotting, and also feed on growing algae and pretty much anything else that they can get their hands on, but they prefer the dead stuff first.

Without these guys there would be heaps and heaps of solid fish and aquatic animal waste floating around.

They managed to turn about 50 lbs of solid fish waste into nothingness in just a few months.

I was working on an aquaponics farm when we one day realized these guys swimming around in the system. At first we had no idea what these guy were, what they were doing in the system, or how they got into the system in the first place. We figured since we hadn’t noticed them all too quickly we should leave well enough alone, but keep a closer eye on the system as time passes… well, what we found out through observation is these guys handled the solid waste problem like it was their job, that’s probably because it is their job. They managed to turn about 50 lbs of solid fish waste into nothingness in just a few months.

During this “watch and lets see what happens” time frame we did a bunch of research on what they could possibly be. The words “gammarus,” and “scuds” kept coming up with pictures that closely resembled what we were seeing, but because of how extremely small they are it was hard to tell at first. One day, we got a camera and waited for one of these little guys to sit still long enough for the lens to focus on it and snapped a picture. what we saw in the picture confirmed what they were, they were indeed these magical animals.

Now, in the arena of aquaponics these guys could be very important. With the Gammarus in the aquaponics system the need for mechanical filtration could be lessened, if not eliminated all together. On a small scale the Gammarus can handle the amount of fish waste coming out of a fish tank in a low density system to the point where no mechanical filtration is being used. This means a more natural ecosystem in the aquaponics system.

Another benefit of the gammarus is the mineralization (big word for breaking down solids) of the fish waste for the plants to use instead of removing these solids with filtration. This means all wastes are being recycled in the system and being fed to the plants.

Now, conceptually, this means you could theoretically run a system on organic waste. You just throw bits of organic wastes into the systems and the Gammarus break it down and in turn the nutrients eat the gammarus waste. This could fix the problem of having to feed fish, which over time can be costly.

Most people are already using Gammarus on a daily basis. Gammarus are dried and sold as quality fish food flakes, so those little red shrimpy things you’re feeding your decorative fish with, those are a species of Gammarus.

Gammarus and Aquaponics

My thought for Gammarus in the future are centered around the world of aquaponics. If a system can be run on a small scale with a low number of fish in a tank to provide a constant stream of waste, and then supplemented other organic waste to the system, this would mean using garbage to make money, if this type of system can be scaled up to the commercial levels… this would be a better alternative to composting. Instead of using organic materials and piling them up and waiting for them to decompose to use as plant fertilizer, you’d take the raw organic materials and add them to your systems for the Gammarus to eat.

If that theory ends up not adding up to efficiency standard of production, you could always find your local aquaculture farm and take some waste from them. Actually, you could have the aquaculture pay you to get ride of their wastes for them and in turn use that waste that you were paid to obtain and turn around and feed it to your Gammarus driven system and make more money. That’s basically killing two birds with one stone. Instead of your feeding cost of the system costing you money, you’d be making money to feed your system, which would grow produce and make you more money.

After looking into this the biggest question I’ve asked myself is, why hasn’t this been thought of before? How is it that aquaponics has been around for so many years and no one has noticed these little guys, or their potential to change the entire industry?

Now that you’ve read this, if you have a system, go and check the stuff floating around the bottom of your system and see if you have these little guys. check you solid settings tanks or anywhere fish poo might be building up…

If you don’t have any Gammarus in your system, you should look into getting them.

If you have them in your system, you now know why fish poo hasn’t been a problem for a while.

Where do you get them?

As it stands right now Gammarus cultures can be bought for a fairly cheep price on the internet. A simple trip through Google with show you many site selling tiny batches of Gammarus that fish breeders use to grow their own high protein fish food. If you don’t want to buy them, you could always go to a nearby lake or stream and start turning over rocks.

Really I just wanted to write this to give proper credit where credit is due. I feel that anything that does a job, and a job as important as waste removal, deserves some sort of recognition. We’ve been relying on these guys for thousands of years and haven’t even noticed their existence. so i think it’s about time to say thank you to the Gammarus for keeping all of our water-ways a bit cleaner just because they are around.

Damon Polta

This guest post is written by Damon Polta who regularly contributes on a number of Aquaponics Forums here in Australia and in the United States. Damon’s motto is “Red is to color of love and rage – life’s greatest irony!”

4 Comments

Wow that’s exciting stuff! I will forward this on to aquaponics guys here in Sydney. Thank you so much – they sound like the black soldier fly of the waterways in terms of bioconversion and feed species.

these guys do wonders for the floating raft systems. really any system that will have a solid settling net tank will benefit from these guys.

the use and understanding of all of the organisms that can call an AP system home will bring the ecosystem closer and closer to full circle. completing the food chain with every link accounted for will bring about the sustainability of an aquaponic system.

there is still much to figure out, but once we start paying more attention to the microbes and detritivores, we’ll be able to have our systems growing their won food just like streams in rivers do… as AP’ers, we’re cutting into mother natures feed portion and not considering the lower ends of the food chain… give a system the space to grow it’s own food by converting the suns energy into micro-edible product, then you’ll have the bottom rungs of the food chain. once you get the bottom rungs established, the need for hand feeding your systems will be a thing of the past.

with a raft system you’re essentially creating a stream… and i don’t know about you guys, but i haven’t seen many people hand feeding the streams they fish from… and yet, the fish still live, and plants still grow on the banks of the water.

Thanks Damon for your excellent article and followup comment. One thing you might want to comment on is the ability of the system to stay pH neutral over time. I remember reading somewhere that the shell of the Gammarus was calcium and this helps (possibly) to buffer the system naturally from becoming too acetic over time which most mature gravel systems without Gammarus tend to do. Is this correct?

many things go into the stabilization of an ecosystem. the calcium in their shell does act as a natural buffer when mineralized by the other detritivores. but we cannot forget that these gammarus are just a part of the system.

in many of the floating raft systems here in the U.S.A. we use mosquito fish as well as the gammarus in the troughs. when the mosquito fish die their bodies are eaten by the detritivores sure as gammarus and their scales, soft bones, and the rest of the dead mosquito fish is cleaned up by the gammarus and other hungry mosquito fish.

but in short, to answer the question, yes. lol. the more natural like the ecosystem becomes, the more the system itself becomes like an animal striving for survival. every organism in the system acts just like the organisms in our bodies, each with their own job and survival in mind individually, but collectively adding balance to the overall systems health. i know that sounds real “down to earth” like, but again i refer to natural lakes and streams as a reference… they don’t need help from people to survive… and since a raft system is just like a stream in many facets, it should be about as equally easy to keep a system healthy as it is to keep a pond or stream healthy. note i said :should be,” because some people’s systems aren’t quite there yet.